Survey: Oncologists Show Support for Erbitux Uptake Based on KRAS Test
The Pink Sheet Daily. 2008 Aug 18, J Merrill
KRAS testing of metastatic colorectal cancer patients could encourage earlier use of ImClone/Bristol-Myers Squibb's Erbitux (cetuximab) in patients with wild type KRAS tumors, suggest the results of a survey of 50 oncologists specializing in the disease.
The KRAS test recently emerged as a way to evaluate which patients are more likely to respond to treatment with epidermal growth factor receptor inhibitors like Erbitux and Amgen's Vectibix (panitumumab).
In a retrospective analysis of data from the CRYSTAL trial presented at the American Society of Clinical Oncology in June, colorectal cancer patients whose tumors contain the wild type KRAS gene responded better to treatment with Erbitux plus chemotherapy than did patients with tumor KRAS mutations. Other studies have also demonstrated the role of KRAS in response to EGFR therapy.
As data on KRAS has emerged so has speculation about what the impact of gene testing and personalized treatment could be on clinical practice. Rodman & Renshaw conducted a survey of oncologists to assess future prospects of Erbitux both in metastatic colorectal cancer and in non-small cell lung cancer - in light of Bristol's bid to buyout Imclone - and released the results Aug. 13.
The investment research firm surveyed 50 leading oncologists, 25 in NSCLC and 25 in CRC, both in academia and in clinical practice, asking them about current treatment practices and future trends. The surveyed docs treat about 4,000 patients in a year.
Oncologists favored Avastin over Erbitux, but just slightly
In the metastatic CRC setting, when asked about their preference for front line treatment of patients with the wild type KRAS gene, the oncologists still favored Genentech's Avastin (bevacizumab) over Erbitux, but only by a small margin (50 percent versus 45.8 percent).
"In our view, this clearly points to increasing acceptance of Erbitux as a viable alternative to Avastin and front-line and second-line mCRC setting in KRAS wild type patients," analyst Michael King said in an accompanying report. "These attitudes are positive for Imclone, and show an unmistakable trend that KRAS testing may actually help Erbitux gain market share."
In the metastatic CRC setting only about 16 percent of patients treated by the surveyed oncologists now receive Erbitux in the first line, with the drug far more frequently used in the second line (68 percent). Erbitux is indicated for CRC in patients whose cancer has progressed after chemotherapy or who are intolerant to chemotherapy.
Avastinwas by far the favored biologic in the front line setting, but was used less frequently than Erbitux in the second line (44 percent versus 68 percent).
About 60 percent of colorectal cancer patients are KRAS wild type, while the other 40 percent have the KRAS mutation, and would be unlikely to respond to EGFR therapy.
When questioned about the role of KRAS testing in treating the disease, a majority of oncologists surveyed (60 percent) said they are incorporating KRAS testing into their clinical practice, while all respondents said they expect KRAS testing will play a "major role" in the management of metastatic CRC.
As diagnostic tests and personalized medicines emerge, however, uptake has been limited, and many questions remain over how payors will cover such tests. Oncologists surveyed by Rodman & Renshaw indicated those challenges will be sorted out.
"We believe physicians are fairly confident that they will not be facing reimbursement hurdles," King wrote. The average doctors expect to pay is about $400 per test.
Extraction, KRAS specimen prep, could pose problem for physicians
Still, of those physicians surveyed, 79 percent were unfamiliar with the technique of preparing KRAS tissue specimens, and 76 percent said they lacked the services of a pathologist for specimen extraction. So establishing KRAS testing in clinical practice could still have a ways to go.
Nonetheless, King expects Erbitux will have a "major impact" on treatment of metastatic CRC in the first and second line in 2009. He increased his estimates of Erbitux market penetration in fiscal 2009 for front line treatment from his current projection of 7 percent to 10 percent; and in the second line setting from 19.3 percent to 25 percent. Those models exclude the impact of KRAS testing.
In addition to the KRAS data from CRYSTAL, Bristol/ImClone also are seeking to expand labeling based on positive results of the Phase III FLEX study, presented at ASCO, showing an overall survival benefit for Erbitux in first line non-small cell lung cancer patients.
An indication in NSCLC could be worth $10.54 to each ImClone share, King speculated.
Bristol announced a bid to acquire the remaining 83 percent of ImClone it does not already own July 31 for $60 per share, or $4.5 billion, a 30 percent premium over the closing price of the stock July 30. ImClone's board of directors has indicated it feels the bid undervalues the firm.
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